Parallel-current calcining-kiln



H. E. BROOKBY. PARALLE'L CURRENT cALclNlNG KILN. `APPLICATION FILED MAR.10, 1919.

Patenteasept. 13, 1921.

' tion, viz.,

process mentloned the temperature at which trate,

ed to me HARRY E. BROKBY, 0F EVANSTON, ILLINOIS.

PARALLEL-CURRENT CALCINmG-KILN.

specification of'tetterrsratent. Patented Sept. 13, 1921.

I Application led March 10, 1919. Serial No. 281,772.

To all whom it concern.: Be it known that I, HARRY citizen of the UnitedStates, residin E'. BRookBY, a at -Evanston, in the county of Cook andtate of Illinois, have invented a certain new and useful Improvement inParallel-Current Calcining-Kilns, of which the following 1s aspecification.

My invention relates. to common' direction or parallel current calciningkilns, and the object of the invention vis to provide a kiln soconstructed that high initial temperatures may be employed, so as toreduce the time of heat treatment to a minimum and yet make it possibleto so accurately control and dis' tribute the heat as to avoidvolatilization or fusion of substances inthe charges that are easilyvolatilized or easily fused. To illusin Patent vNumber 1,297,078, grant-Marchv 11, 1919`,I have described a process for obtaining a watersoluble potassium compound from hydrous, potassium bearing silicates,and it is important in that process to avoid the volatilization of anyappreciable amount of the potassium comound. For commercial reasons itisdesirable to fire the kiln with powdered coal instead of employingliquid or gaseous fuel.

vBut powdered coal requires quite a high maintain combustemperature toproperly C. whereas in the about 1500o the reaction should take place(and to which it must be limited during the reactive period if theprocess is to be efficiently carried out) is much lower than this. Mypurpose is to make it possible to deal with high initial temperatures,and specifically to use powdered coal as fuel, and at the same time makeit possible to efliciently practice p rocesses having heat limitationssuch as typified in the process described in my said patent.

Other objects of the invention are to provide means for completing theheat treatment effectively and inl a minimum perio of Atime and with aminimum amount of fuel; to render the process continuous; to

make'it possible for the apparatus to remain long. in service withoutrequlring repairs ;l

Figure 1 is a longitudinal '.vertical section` tudinal axis.

d be drawnV back from the hed of the 'complete apparatus omitting thelower or far end of the kiln proper.

vF 1g. 2 is a. transverse sectional elevation on the line 2-2, Fig. 1.

.Like numerals denote like parts in both vlews. E Y

` In the form selected to illustrate the invention, the kiln properconsists of a shell comprlsing a lining 2 of fire brick er otherrefractory material. The shell is supported so as to be able 15o-'rotateabout its longitudinal axis, 1t being suiicient for the present purposeto show but one of the supports, which consists of an annular track 3encircling the shell and running upon a flanged roller 4 journaled in abearing 5 y'mounted upon a pedestal 6. The axisof the shell is tilteddownward from the head or receiving end, and suitable means (not shown)are provided for rotating the shell about its longi- In this artit iscommon to employ the term countercurrent kilns for those in which thegases move inone direction and thecharge moves in the oppositedirection.

Where the gases and the charge movev through the kiln in the samedirection, the apparatus is referred to as a parallel current kiln. Myapparatus is a parallel current kiln.

The head end of the' shell is closed by a non-rotary hood 8 which has anannular Bange 9 inclosing and making a running fit with the shell. Thehood consists of refractory -material and is mounted upon a truckframelO having four flanged wheels 11, 11 adapted .to travel'upon rails12, 12 arranged .longitudinally of the kiln. The rails aire mounted upona suitable foundation or pedestal 13 and :the construction andarrangement are such that when repairs are necessary the entire hoodwith the parts car- Tied-thereby (presently to be described) may g endof the shell a distancesufficient to Aafford access thereto.

By preference holes 14 are placed in the hood to afford means forintroducing secondary air, also to facilitate inspection.

The hood has a comparatively large opening near the bottom into which.fits a combustion chamber 15. By vpreference this consists of acylindrical -metallic casing 16 having a lining 17 of refractorymaterial.

and the combustion chamber 15 move with `While the dimensions may ofcourse be varied, in a kiln whose shell is about 6 feet in diameter thecombustion chamber may appropriately be approximately 3 feet in diameterand 6 feet long and extend about 2 feet more orless into the shell.Although the combustion chamber makes a comparatively tightfit in thehood 8, it is desirable to afford it sufficient play to enable it to berotated by hand about its longitudinal axis occasionallyfor example,once every day or so to equalize the wear.

Fuel, preferably in 'the form of powdered coal, is introduced into thecombustion chamber through the head v19 thereof, by means of a pipe 20.Peep holes 22 are formed in the head of the combustion chamber, thesebeing normally closed by suitable plugs 23.

'llhe material which is to be heat treated is introduced into the kilnby a continuous feed apparatus consisting preferably of a worm or screw26 working in a cylindrical casing 27 and mounted upon a shaft 28 drivenby a pulley 29. The material is fed into the casing 27 by a hopper 31which in the best form is mounted upon and removable in unison with thecasing 27. Said casing is supported by the hood 8 of the kiln with theresult that when the hood is withdrawn from the end of the kiln both thefeed mechanism it. A storage bin 35 is supported in fixed position bystationary beams 36, 36 or other suitable supports. The flow lofmaterial from the bin to the hopper is controlled by a shut-.off valve37 of any suitable design.

rllhe casing 27 extends a short distance into.the shell of the kiln,preferably for a distance of 6 to 12 inches. Secured vto shaft v28 andspaced a few inches from the inner end of casing 27 is a deflector 40.This deiector has rotating vanes`or paddles which brush aside, fromol'l'l the top of the vcombustion chamber, the material which wouldotherwise tend to collect there.

In operation, the shell 1, 2 of the kiln is started rotating and thesupply of fuel turned on. When powdered coal is used, as'

particularly contemplated in my apparatus, combustion is started inchamber 15 by withdrawing one of the plugs 23 and inserting conveyer.

plug replaced. As soon as the valve 37 is slid to open position, thematerial to' be heat treated will enter the 'hopper'31 and be directedby it into the casing 27 of the screw x The screw is rotatedcontinuously and hence the process is continuous.

As above stated, to insure maintenance of combustion of powdered coal, atemperature in the neighborhood of 1500o C. must be maintained, whichtemperaturewould tend to volatilize and fuse many substances and thusinterfere with the proper carrying on of such processes as I have abovereferred to. But with my apparatus the combustion chamber is long enoughto enable the gaseous contents to acquire a more or less uniformtemperature throughout their volume before they 'leave the combustionchamber. Furthermore, the cold material falling upon the outside of thecombustion chamber tends to cool it slightly, thus reducing thetemperature of the emerging gases somewhat below the highest temperaturein the chamber. rllhe result is that by this arrangement the coldmaterial is introduced at the side of the entering `blast and thetemperature of the blast tends to be reduced somewhat and thetemperature of the cold material raised somewhat before the. gases andthe charge come into contact with each other. Another advantage in thusintroducing the material at the side of the blast is thatit eliminatesdust losses. Due to handling, some of the .material becomes powdered bythe time it leaves the feed mechanism. By keeping this away from theblast it prevents the blast from" blowing the powder orl dust outthrough the kiln. lin my apparatus also, the preheating period-that is,the period during which the material is being raised to the temperatureat which the reaction will occur, occurs in that portion of the kilnwhich is hottest; and the critical portion of the process occurs inthose parts of the kiln which are relatively cooler and where thetemperatures may be more accurately controlled.

l bring the inner end of the combustion chamber a considerable distancein through the hood and bathe the surface of the combustion chamber, soto speak, with the incoming material which is to be treated. Suchoperation causes the temperature of the gases of combustion .to bereduced somewhat before coming into contact with the charge. By the sametoken, the temperature of the charge is elevated somewhat, with theresult that it does not have to be raised so high when it does meet thegases before the reaction commences to take place. In other words, thereis a tempering or equalizing of the temperatures to a certain extentbefore the two things mingle, thus not only saving time but precludingthe danger of volatilizing some of the valuable constituents of l thecharge.

My apparatus is therefore particularly adapted for processes such as theone herein above mentioned, and in addltion the process 1s continuousand efficient and when repairs become necessary access to the` parts mayeasily be obtained by simply rolling back the hood 8 on the tracks 12.As all the opconveyer being within said shell.

eratingvparts except the rotating kiln itself are mounted upon the hood,repairs become a comparatively simple matter, for when the hood is drawnback access is afforded to the inner end of the parts on the hood aslwell as to the interior of the body vof the kiln. By rotating thecombustion chamber about its axis once every day or two, any Swear whichma occur from the constant dropping of t e material ontothe top of thecombustion chamber maybe distributed over the entire inner end of thecombustion chamber and hence the wear becomes practically a negligibleconsideration. The heat and Veloclty of the burning fuel passing throughthe combustion chamber tends to wear and channel it. By rotating the.combustion chamber occasionally, the wear becomes equally distributed.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent, is

1. A common direction, calcining kiln having a rotary shell, acombustion chamber projecting into the shell, and means for introducingthe charge into the shell and passing lit over a portion o surface ofthe combustion chamber for raising the temperature of the charge andlowering the temperat re of the gases of combustion before the twomingle in the shell.

2. A common direction, parallel lcurrent calcining kiln having a rotaryshell, a combustion chamber projecting into the shell, means forintroducing into said combustion chamber fuelbelow the temperature ofignition, means for introducing the charge into said shell and passingit over a portion of the surface of said combustion chamber parallelcurrent,

.3. A common direction parallel current calcining kiln having a rotaryshell, a combustion chamber projecting into the shell,

and means for dropping the charge onto the projecting portion o-f thecombustionA chamber. .j

4. A parallel current kiln having a rotary shell provided with a hood, acylindrical combustion chamber arranged substantially lengthwise of theshell for directing the hot gases of combustion into it, and a screwconve er mounted in the'hood and arranged paral el and adjacent to thecombustion chamber for delivering a'continuous chargev into the shell,the delivery end of the screw above the combustion chamber andterminating short ofthe delivery end thereof, so as to drop the materialto be treated on to the top of the combustion chamber.

5. A parallel current kiln having a rotary chamber at a f the bustionchamber 6. A parallel current kiln having a rotary l shell, a hoodmovable longitudinally toward and from the head ond of the shell, andadapted to form a closure therefor, a c0111- bustion chamber forintroducing hot gases into the shell, and continuously operating meansfor feeding the charge into the shell, said combustion chamber and thefeeding means being mounted upon the hood.

7. A common directionl parallelcurrent kiln having a cylindrical rotaryshell, a

hood closing the head thereof, a combustion chamber mounted in the hoodand extending a considerable distance into the shell from the inner faceof the hood, and means for delivering the charge onto the combustionoint between the inner' face of the hood and) the inner end of thecombustion chamberA the charge is raised land thetemperature j of theproducts of combustion are reduced before the two mingle in the shell.

8; A parallel current calcining kiln having a cylindrical rotaryshell,'a hood closing the. headv end thereof, a combustion chamberextending an ap reciable distance into 'the shell from the inner face ofthe hood, and a screw conveyer mounted inthe whereby the. temperatureofl hood and'having its inner end located above the combustion chamberand projecting yabout half-as far into the kiln as the combustionchamber does, said combustion chamber being cylindrical, and the screwconveyer being located centrally above the combustion 5chlamber fordischarging the material onto the top of it.

9. A parallel current calcining kiln having a rotary shell, a hoodforming a closure for the head end of the shell, and a cylindricalcombustion-chamber mounted in the hood and rotatableabout itslongitudinal.

axis.

10. A parallel current calcining kiln having a rotary shell, a hoodforming a closure for the head end of the shell, a cylindricalcombustion chamber projectin a considerable distance into the head en ofthe and a conveyer adapted tol dro the material to be treated onto thetop o? the inner end of the combustion chamber, said combeing rotatableabout its longitudinal axis to 'distribute the wear caused by thedropping material.

11. A common direction parallel current kiln having a cylindrical rotary-`shell, a hood closing the head thereof, a combustion shell,

chamber mounted in the hood and extending a considerable distance intothe shell from the inner face of -the hood, means for intro-' ducng intosaid combustion chamber fuel below the temperature of ignition, andmeans for delivering the charge in an approximately continuous stream fonto the combustion chamber at a poinl between the inner face of thehood and the inner end of the combustion chamber and causing the 10charge to pass down around the surface of said combustion chamber.

ln witness whereof l have hereunto subscribed my name.

HARRY E. BROOKBC

